1. Field of the Invention
The present invention relates to a locking nail for treating femoral fractures in the medium and trochanter region. More particularly, the invention relates to a locking nail having a closed first section and an open second section containing longitudinal slot.
2. Description of the Prior Art
An osthesynthesis device to be used for sub-trochanter fractures is disclosed in European Patent 0 257 118, which device comprises a closed locking nail including an oblique bore for guiding and positioning a femoral neck screw in the proximal portion thereof. Since the locking nail, known as well as the "Gamma Nail" (shown in copending U.S. Ser. No. 281,730, filed Dec. 9, 1988), is not used itself for treating fractures of the femur neck, the nail is shorter than usual, merely including cross bores in its distal portion to fix the nail in an axial and rotational direction. A nail having a varying radius through its cross-section is shown in U.S. Pat. No. 4,976,258, which issued to the assignee of the present invention.
The femur neck screw fits in the oblique bore and is thus effectively secured against pivoting in the plane clamped thereby and about an axis defined by the locking nail. To rotatably secure the femur neck screw a rotational lock, for example, a locking pin is provided. This rotational lock allows the femur neck screw to axially move so that the screw may yield when the bone shortens during healing.
While the known locking nail according to European Patent 0 257 118 has a closed profile, the so-called Kuntscher Nail has an open clover leaf profile having a longitudinally extending slot. The strength of the mechanical attachment in the marrow space or medullary canal, in particular the rotational stability of the Kuntscher Nail, can be improved by use of the present invention.
An advantage of a slotted nail is seen in its elasticity resulting from the axial longitudinal slot so that a certain spring effect is obtained, and as the nail is hammered in, it is laterally pressed against the bone material.
The nails referred to are used in the treatment of fractures in the central third or, respectively in the sub-trochanteric region. However, these nails are less suited for the treatment of complicated femoral fractures.